1. Field of the Invention
This invention relates to hydrocarbon hydroprocessing catalysts, such as those utilized to catalyze the reaction of hydrogen with organonitrogen, organosulfur and organometallic compounds. More particularly this invention is directed to a catalyst useful for the hydrodesulfurization, hydrodenitrogenation and hydrodemetallation of hydrocarbon-containing feeds, such as residuum oils, and to a method for preparing such catalysts with porous, amorphous refractory oxide supports.
2. Description of Prior Art
In the refining of hydrocarbons, it is often necessary to upgrade a hydrocarbon-containing oil, such as a residuum, by hydroprocessing. Among the known hydroprocesses are hydrodesulfurization, hydrodenitrogenation and hydrodemetallation wherein feedstocks such as residuum-containing oils are contacted with catalysts under conditions of elevated temperature and pressure and in the presence of hydrogen so that the sulfur components are converted to hydrogen sulfide, the nitrogen components to ammonia, and the metals are deposited (usually as sulfides) on the catalyst.
Hydroprocessing is usually carried out with a catalyst containing Group VIB and Group VIII hydrogenation metal components on a refractory oxide support.
Generally, hydroprocessing catalysts having a substantial number of pores of diameter less than 120 angstroms are effective for catalyzing desulfurization and denitrogenation reactions in residuum feedstocks, while catalysts having a substantial amount of pore volume in relatively larger pores (particularly pores of diameter greater than about 150 angstroms) are effective for removal of contaminant metals (such as nickel and vanadium) from such feedstocks. In other words, hydroprocessing catalysts having pores of relatively large size have demonstrated greater effectiveness for demetallation of a residuum feedstock than catalysts of smaller sized pores.
Although conventional catalysts are active and stable for hydrocarbon hydroprocessing reactions, catalysts of yet higher activities and stabilities are still being sought. Increasing the activity of a catalyst increases the rate at which a chemical reaction proceeds under given conditions, and increasing the stability of a catalyst increases its resistance to deactivation, that is, the useful life of the catalyst is extended. In general, as the activity of a catalyst is increased, the conditions required to produce a given end product, such as a hydrocarbon of given sulfur, nitrogen, and/or contaminant metals content, become more mild. Milder conditions require less energy to achieve the desired product, and catalyst life is extended due to such factors as lower coke formation or the deposition of less metals. The search continues for catalysts which are still more active for catalyzing both demetallation and desulfurization reactions during hydrocarbon hydroprocessing, yet are also stable.